The purpose of the methodology studies undertaken here is to prepare for large and/or definitive projects that examine the role of environmental toxicants in reproductive outcome. Methodology studies may address one part of a difficult investigation (such as validity of measurement), or they may be a pilot to highlight difficulties in a future study to be resolved, or they may be small studies using an accessible agent (rather than a rare environmental exposure) to elucidate mechanisms by which toxins affect reproductive health. This year methodology studies have centered on the Aral Sea region to determine if sufficient information can be obtained from this region to warrant additional investigation. We have two pilot data sets that describe reproductive outcomes in the area. Analysis of one data set is complete; major findings were the extremely high rate of anemia (99%) in the region, and the excess of macrosomic infants. The second data set has been coded and is now being analyzed. Another methodologic study has addressed sibling traits in SIDS families. Methodologic work in reproductive epidemiology using alcohol as a prototypical agent is ongoing.